An AMOLED (Active Matrix Organic Light-Emitting Diode) is able to emit light as it is driven by a current generated by a driving TFT in saturation; that is to say, the AMOLED is driven by the current to emit light. FIG. 1A is a schematic diagram showing a pixel structure of an AMOLED of an existing elementary current type, and FIG. 1B is a timing sequence chart corresponding to the same. As shown in FIG. 1A, the pixel structure of the AMOLED of the existing elementary current type includes an OLED (Organic Light-Emitting Diode), transistors T1, T2, T3, and T4, and a storage capacitor Cst, wherein T1 is a driving thin film transistor, T2, T3 and T4 are controlling thin film transistors; a gate of T2 and a gate of T3 are connected to a control line for outputting a control signal CN1, and a gate of T4 is connected to a control line for outputting a control signal CN2. A driving current Idata is directly applied to the pixel structure of the AMOLED of the existing elementary current type externally to determine a voltage across the storage capacitor Cst, thus generating a driving current Ioled for driving the OLED to emit light. In the pixel structure of the AMOLED of the existing elementary current type, Ioled is equal to Idata, and since bled must be in the range of the operating current of the OLED, i.e., Ioled must be a relatively small current, Idata should be relatively small. As the storage capacitor Cst is a large capacitor, the speed for charging the storage capacitor Cst is relatively slow; especially at a low grey level, it takes a long time to charge the storage capacitor Cst. Therefore, the pixel structure of the AMOLED of the existing elementary current type is not suitable for an AMOLED display of high definition and high refresh frequency.